A novel four phase AC electroosmotic micropump for lab-on-a-chip applications

Pumping of fluids with low Reynolds number is one of the main challenges in lab-on-a-chip and “micro total analyzer” devices. Any downscaling of channels which is used microfluidics components in such systems intensified the phenomena. Application of the electroosmotic micropumps is suitable for very low Reynolds number. In this paper a modified fabrication process presented to design an “AC electrokinetic micropump” with minimized channel geometry. The proposed device is a 4-phase travelling wave electroosmotic micropump, which is fabricated by surface micromachining technique. During the fabrication process, a thin silicon nitride layer covers the electrodes. The pumping performance is studied by presence of this thin insulator layer. This study reveals that the pump operates if the electric conductivity of fluid buffer is low. Additional advantage of the insulator layer over electrode arrays is the preventing of high electric field on electrode edges and consequently undesired chemical reactions, like electrolyze. The fabrication process and results of finite element analysis is presented. The maximum flow rate of “2.39 mm/s” is obtained at a wide frequency range.